U.S. patent number 6,772,932 [Application Number 10/303,358] was granted by the patent office on 2004-08-10 for automated welding system utilizing overhead robots.
Invention is credited to Scott P. Halstead.
United States Patent |
6,772,932 |
Halstead |
August 10, 2004 |
**Please see images for:
( Certificate of Correction ) ** |
Automated welding system utilizing overhead robots
Abstract
An automated welding system utilizing integrally mounted robots
within a self-contained and repositionable work station. One or
more work tables are shuttled between loading and welding stations.
The robot is mounted directly adjacent the operating stage, thereby
drastically reducing the required floor space. The robot arm is
designed to be programed to replicate a desired welding operation
in an automated fashion.
Inventors: |
Halstead; Scott P. (Jackson,
MI) |
Family
ID: |
32823635 |
Appl.
No.: |
10/303,358 |
Filed: |
November 25, 2002 |
Current U.S.
Class: |
228/45;
219/125.1; 901/42 |
Current CPC
Class: |
B23K
37/0235 (20130101) |
Current International
Class: |
B23K
37/02 (20060101); B23K 009/00 (); B23K
037/02 () |
Field of
Search: |
;219/125.1 ;901/42
;228/45 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
US2002/0139780 A1 Jones et al. (Oct. 3, 2002--10/095,529 filed Mar.
13, 2002)..
|
Primary Examiner: Stoner; Kiley
Assistant Examiner: Kerns; Kevin P.
Attorney, Agent or Firm: Young & Basile, P.C.
Claims
What is claimed is:
1. An apparatus for welding, comprising: a self-contained, portable
enclosure defining a work space which further comprises one or more
side walls, a bottom frame, a top frame and one or more side
frames; a table frame affixed to said bottom frame, said one or
more side frames with or both; at least one work surface
selectively positionable on said table frame between a loading
position and an operating position; at least one robot positioned
above said work surface; at least one window disposed in at least
one side wall; at least one shutter disposed on said at least one
side wall and selectively positionable to cover and uncover said at
least one window; drive means mounted within said work space for
positioning said at least one robot and said at least one work
surface; sensor means mounted within said work space for
determining the positions of said at least one robot and said at
least one work surface; computer means affixed to said enclosure
for controlling said drive means and said sensor means; and a
welding head mounted to said at least one robot.
2. The apparatus of claim 1, wherein said robot is mounted to said
top frame.
3. The apparatus of claim 1, wherein said robot is mounted to one
of said one or more side frames.
4. The invention of claim 1, which further comprises said at least
one work surface positionable on a linear axis between a loading
position and an operating position.
5. An apparatus for welding, comprising: a self-contained, portable
enclosure defining a work space which further comprises one or more
side walls, a bottom frame, a top frame and one or more side
frames; a table frame affixed to said bottom frame, said one or
more side frames with or both; a pair of adjacent work surfaces
selectively positionable on said table frame between a loading
position and an operating position; at least one robot positioned
above said work surface; at least one window disposed in at least
one side wall; at least one shutter disposed on said at least one
side wall and selectively positionable to cover and uncover said at
least one window; drive means mounted within said work space for
positioning said at least one robot and said at least one work
surface; sensor means mounted within said work space for
determining the positions of said at least one robot and said at
least one work surface; computer means affixed to said enclosure
for controlling said drive means and said sensor means; and a
welding head mounted to said at least one robot.
6. The invention of claim 5, wherein each of said pair of
selectively positionable work surfaces is positionable on a linear
axis between a loading position and an operating position.
Description
FIELD OF THE INVENTION
The invention pertains to automated robotic welding systems, and
more particularly, to self-contained welding stations.
BACKGROUND OF THE INVENTION
Dedicated work areas, frequently referred to as "work cells" or
"work stations" are well known in the industrial arts. Particularly
in the area of welding, the use of such work cells or work stations
is common, because of the benefits associated with the strict
enclosure of the welding operation, and isolation of the welding
operation from the surrounding industrial environment.
Work cells or work stations equipped with robots are also well
known. See, for example, U.S. Pat. No. 4,695,027, issued to
Lindholm, and U.S. Pat. No. 6,274,839 B1, issued to Stone.
One of the drawbacks associated with prior art welding stations, in
particular, has been the necessity for secure mounting of the robot
head in relation to the workpiece to be welded. Conventional wisdom
teaches that the robot head must be securely mounted to the factory
floor, or to the base of the work cell or work station. While
overhead mounted robots have been successfully used in certain
applications, such as that taught by Cahlander in U.S. Pat. No.
4,922,435, there remains a need for a self-contained welding-type
work station wherein the robotic head is mounted integrally to the
work station and above the stage within the station where the
welding operation will take place. This methodology provides the
benefit of creating a unitary and transportable work station which
is compact, preserving precious industrial floor space, yet still
allowing the entire assembly to be positioned, installed, and if
necessary, relocated within the industrial environment.
SUMMARY OF THE INVENTION
The invention is an automated welding system utilizing overhead
mounted robots within a self-contained and repositionable work
station. The invention utilizes a "shuttle" work table system,
which includes one or more tables which shuttle to and from a
position adjacent to the operating elements associated with the
robotic arm. The invention incorporates overhead mounting of the
robot directly over the operating stage, thereby drastically
reducing the required floor space. The application can be used with
either single or multiple robotic arm assemblies.
Further, the invention incorporates a structure forming an
enclosure and supporting a robotic arm assembly. The robotic arm
assembly is designed to operate within an operating stage served by
one or more shuttling tables. An automated welding operation takes
place within the confines of the enclosure, which protects the
surrounding area from the byproducts of welding, protects nearby
workers from those byproducts, and encloses the potentially
dangerous light emissions from the welding process.
The welding equipment itself may be any of the conventional arc,
MIG, TIG, or other common welding techniques readily adaptable to
robotic tools.
The work station is built upon a sturdy perimeter frame comprised
of one or more elements, including a ceiling frame, a floor frame
and side wall frames. Side wall frames are provided with covers
which form the enclosure. The covers themselves may be equipped
with one or more openings, likewise provided with shutters. Mounted
to the outside of the enclosure are one or more power supplies and
one or more enclosures for operating elements such as motors,
sensors, controllers, computers and the like
The welding robotic arm assembly is conventional in all respects,
and may have either fixed or movable track mounting. Likewise, the
robotic arm assembly may utilize a turntable mounting, including a
base rotor assembly which is positionable using a drive system and
having appropriate feedback means, typically utilizing stepper
motors. The robot arm has one or more articulating joints for
selective positioning of the robot arm in all three axes within the
enclosure, as well as rotating joint elements. The end of the robot
arm is provided with a welding tool appropriate to the welding task
to be performed. Utilizing the positioning features above
described, the robot arm can be positioned in any predetermined
location about the operating stage.
The shuttle tables are provided with bearing surfaces to
accommodate sliding table elements. The sliding elements have a
top, bottom, side and ends and are positionable on the bearing
surfaces by appropriate drive means having associated feedback
means.
In operation, one or more work pieces are positioned in
predetermined locations on one or more work tables. Work tables are
automatically positioned utilizing the aforedescribed drive means
to the operating stage. Program logic or machine vision software,
or both, provide instructions to the robot for correct positioning
of the robot operating elements in relation to the workpiece and
performing of the welding operations.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the work station according to the
present invention showing the basic relationship of the side walls,
frame work and operating and loading stations.
FIG. 2 is a front view of the invention showing a single robot.
FIG. 3 is aside view of the invention.
FIG. 4 is a top view of the invention embodiment with dual work
tables.
FIG. 5 is a perspective view of the invention embodiment with dual
work tables and dual robots.
FIG. 6 is a front view of the invention embodiment with dual work
tables and dual robots.
FIG. 7 is a side view of the invention embodiment with dual work
tables.
FIG. 8 is a top view of the invention embodiment with dual work
tables and dual robots.
FIG. 9 is a perspective view of the invention embodiment with rear
wall mounted robot.
FIG. 10 is a side view of the invention embodiment with rear wall
mounted robot.
DETAILED DESCRIPTION OF THE EMBODIMENT
An understanding of the structure and operation of the invention
will be apparent from the following description, and reference to
FIG. 1-10. The invention is a welding station 10 enclosing an
enclosed work space 30. The enclosure typically comprises a left
side wall 12, a right side wall 14, a rear side wall 16, a top
frame 20 and a bottom frame 22. In one embodiment, the enclosed
work space is further defined by a welding curtain 18. Side walls
12, 14 and 16 are typically constructed around one or more side
frame elements 24. The side walls 12, 14 and 16 are preferably
metal, for example, steel or aluminum and are designed to enclose
the work space 30 and to contain the byproducts of the welding
operation, as well as protect workers in the immediate area from
the potentially dangerous electrical or gas energy associated with
the welding process, and protect workers from the equally dangerous
high intensity light generated by the welding process. Side walls
12, 14 and 16 are attached to the top frame 20 and bottom frame 22
and side frames 24 using conventional fasteners in a well known
manner, thereby creating a sturdy enclosure surrounding an enclosed
work space 30 and a semi-enclosed loading area 31.
Side walls 12, 14 and 16 are preferably provided with windows 32 to
allow access to the work space 30 when the welding operation is not
in progress. This access may include access for maintenance to the
components internal to the workspace, for inspection of the results
of the welding operation, repositioning of workpieces upon which
the welding operation is being performed, maintenance of other
components within the welding station 10 and programming of the
robot 50. Windows 32 are provided with shutters 34 which are
typically mounted utilizing shutter hinges (not shown), although
shutters 34 may likewise be mounted on tracks or guides to permit
shutters 34 to be opened and closed in relation to windows 32 in
areas where clearance for opening the shutters 34 is limited.
Shutters 34 are provided with latches 37 to secure the shutters in
a closed position prior to the welding operation. Additionally,
shutters 34 are provided with interlock sensors (not shown) which
provide an electrical signal corresponding to the condition of the
shutter. In this fashion, an electrical signal confirming that the
shutter is in the closed position is available for a controlling
device, for example, a computer, to prevent operation of the
welding robot itself when any of the shutters 34 are in the opened
position.
Located within the welding station 10 and suspended from the top
frame 20 is a robot assembly 50.
The welding station 10 is typically used for fabrication of complex
assemblies from individual components in the form of workpieces.
Workpieces are placed on and frequently secured to a work surface
40, the upper surface of a movable table 42 slidably supported on a
table frame 44. Table frame 44 is provided with guiding carriages
47 which engage rails 45, thereby allowing tables 42 to be moved in
relation to table frame 44 from a position in the loading position
31 to the operating position 33. Tables 42 are typically driven by
either electrical or pneumatic means, and their position reported
by the sensors associated with the guide carriages 47 and rails 45.
Utilizing this method, the location of tables 42 in relation to the
table frame 44, the operating station 33 and the loading station 31
can be ascertained, and the data regarding that position fed to a
computer (not shown). In one embodiment, two tables 42 are
provided. Use of two tables 42 allows a welding operation to take
place within the enclosed workspace 30 on a workpiece positioned on
the work surface 40 and a table 42 while a second table 42 can be
positioned in the loading area 31 allowing the operator to remove,
reload and secure a succession of workpieces without significant
interruption in the operating cycle. In this fashion, a welding
operation can be taking place simultaneously with a loading or
unloading operation. The presence of a curtain 18 protects the
operator from the hazards associated with the welding operation
taking place behind the curtain 18.
The welding operation will be better understood by reference to
FIGS. 3 and 4, which show the parked position of the robot 50. In
this embodiment, a robot 50 is mounted to a robot base 52. The
robot base 52 is in turn mounted to the top frame 20 of the welding
station 10. By positioning the robot 50 on the top frame 20,
support is provided for the robot head within the welding station
10 operating station 33 without the need for a separate mounting
pedestal or support adjacent to the welding station 10. Robot 50 is
provided with motors (not shown), articulating joints 56 and a
welding head 58. Preferably, the motors are digitally operated
stepper motors having feedback means, enabling the position of each
motor to be reported to the computer (not shown).
Under control from the computer (not shown) detailed instructions
regarding the positioning of the welding head 58 by the motors may
be accomplished. Further, the work table is preferably provided
with sensors 60, also connected to the computer (not shown).
Sensors 60 may be video devices, tactile sensors or magnetic
sensors Additional sensors 60 may be programmable to recognize the
position, surface and dimension attributes of the workpiece.
Therefore, in addition to being pre-programmed to perform welding
operations under the control of the computer or robot controller
(not shown), the welding head may be provided with means for
verifying and improving the position of welding head 58 prior to
execution of any weld. In a typical application, the welding
operation involves one or more welds carried out under the control
of the computer (not shown). The welding head may perform a single
welding operation, a continuous weld operation, or a series of
welds depending on the requirements of the particular job.
A typical sequence for operation of the machine begins with the
loading of the workpiece by an operator on the work surface 40 of
table 42. The operator then cycles a control (not shown), which
continues the sequence. The next step in the sequence is the
transport by the table drive system of the table from the loading
area 31 to the operating workspace 30. Because curtain 18 is
flexible, movement of the table 42 and associated workpiece pushes
the curtain 18 temporarily up until the table has passed into the
operating position, which permits the curtain 18 to fall back under
the force of gravity to a more or less vertical orientation. Next,
the sensors 60 verify the presence and position of the workpiece in
a vicinity of the welding head 58 of the robot 50. The robot motors
54 are then instructed to position the various articulating joints
56 of the robot 50 to position the welding head 58 adjacent to the
point of the first weld. A signal is then provided to the robot
welding head 58 to initiate the weld. This procedure continues for
all welds required for the workpiece. Once the computer has
instructed the robot 50 to complete its final weld, the computer
then instructs the table 42 to move from the operating position 33
to the loading position 31 where the now welded workpiece can be
removed by the operator and transferred to the next industrial
processing station.
In a second embodiment of the invention as shown in FIGS. 5-8, a
pair of robots 50 operate side by side, and the welding station 10
is provided with a pair of tables 42. Utilizing this scheme, one
table 42 may be in the operating position 33 undergoing the welding
operation by the robot 50 while the other table 42 is in the
loading position 31, being either loaded or unloaded by the
operator.
To insure the safety of the operator, as well as the safety of
persons in the vicinity, the computer (not shown) is programmed to
lock out any welding operations when any of the shutters 34 is in
the opened position, or when no table 42 is in position under the
welding head 58 in the operating position.
The entire welding station 10 is constructed as a transportable
unit, permitting the welding station 10 to be lifted by its bottom
frame 22 or top frame 20, and repositioned within the manufacturing
facility. The robot 50 and its associated motors 54, and
articulating joints 56 and welding head 58 are articulatable
through essentially the entire interior portion of the interior
portion of the enclosed workspace 30 defined as the operating
position 33. The robot 50 is provided with full x, y and z axis
movement by virtue of the articulating joints 56 and base 52. This
insures that the robot head 58 may be positioned in relation to any
exposed portion of the workpiece affixed to the work surface 40 of
table 42.
The top frame 20, bottom frame 22, side frame 24 and table frame 44
are constructed from rigid frame members, typically of steel or
aluminum alloys welded together in a well known fashion. A control
computer, electrical connectors, transformers, and other power and
control elements are enclosed within a protective enclosure 11. Top
frame 20 may be provided with rails 23 and robot base 52 may be
provided with rail engaging carriers (not shown) to permit the
robot base 52 to move from side to side within the enclosed
workspace 30 of the welding station 10. Such movement may be
manually or computer-controlled.
In yet another embodiment of the invention as shown in FIGS. 9 and
10, one or more robots may be mounted to the side frame 24. In this
embodiment, the robot base 52 may be mounted to a side frame 59 of
the welding station 10.
Programing of the robotic welding operation above-disclosed is
generally accomplished through the use of a teaching pendent 60
electronically connected to the computer. Utilizing this
methodology, the robot may be positioned to each desired welding
point on a workpiece by opening the shutters 34 and positioning a
workpiece, utilizing appropriate tooling, on table 42 positioned in
the operating position. The pendent 60 is equipped with controls
which permit an operator to cause the robot 50 to be moved to a
particular welding position. Each movement of the robot, including
operation of the welding tool, is memorized by the computer as an
operator manually positions the robot 50 and welding head 58
utilizing the pendent. The entire sequence of operations is stored
by the computer in its memory for later recall. Upon recall, the
precise movements of the robot 50 are replicated by the computer.
The sequences of instruction provided by an operator utilizing the
teaching pendent 60 may be memorized by the computer and stored in
volatile, non-volatile or removable memory devices, such as
computer disks. Once the sequence of operations for a particular
welding task has been taught to the computer, the teaching pendent
60 may be disconnected or disabled, and the shutters 34 over the
openings 32 are closed prior to engaging in the actual welding
operation utilizing the stored sequences afore described.
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